Gaseous exchanges of corn and weeds under competition and water regimes/Trocas gasosas do milho e de plantas daninhas sob competicao e regimes hidricos

• Published in: Revista brasileira de engenharia agrícola e ambiental 2020-07, Vol.24 (7), p.465
• Main Authors: Freitas, Claudia D.M, Pamplona, Juliana de P, Lins, Hamurabi A, Souza, Matheus de F, Dombroski, Jeferson L.D, Silva, Daniel V
• Format: Article
• Language: English
• ISSN: 1415-4366
• DOI: 10.1590/1807-1929/agriambi.v24n7p465-473

Water deficits can alter vital physiological functions and negatively affect plant growth. These effects can be intensified by weeds competing for water available to crops. The objective of this study was to evaluate the effects of competition and temporary soil water deficit on the transpiration (E), stomatal conductance (gs) and photosynthetic rate (A) of corn, Urochloa decumbens, and Bidens pilosa L. The experimental design was in randomized blocks with eight repetitions. The treatments were arranged in a 5 * 2 factorial scheme, with the first factor corresponding to the species: corn + U. decumbens, corn + B. pilosa, and corn, U. decumbens, and B. pilosa without competition. The second factor was two water regimes: daily irrigation and water restriction, which corresponded to the suspension of irrigation from the beginning of the V3 stage of corn until the time when their stomata were completely closed. The species B. pilosa and U. decumbens worsened the negative effects on E, gs, and A of corn at different intensities under water restriction. The U. decumbens was more aggressive in relation to B. pilosa while coexisting with corn in both water regimes. The competition with corn affected the E and gs of U. decumbens in the two water regimes, but the A was altered under water deficit. On the other hand, the physiological components of B. pilosa were not affected by its coexistence with corn in the two water regimes. Keywords: Zea mays L., Urochloa decumbens, Bidens pilosa L. O deficit hidrico pode alterar funcoes fisiologicas vitais e afetar negativamente o crescimento das plantas. Esses efeitos podem ser intensificados pelas plantas daninhas que competem pela agua disponivel para as culturas. O objetivo foi avaliar os efeitos da competicao e do deficit hidrico temporario do solo sobre a transpiracao (E), condutancia estomatica (gs) e taxa fotossintetica (A) do milho, da Urochloa decumbens e da Bidens pilosa L. O delineamento experimental foi em blocos casualizados, com oito repeticoes. Os tratamentos foram arranjados em esquema fatorial 5 * 2, com o primeiro fator correspondente as especies milho + U decumbens, milho + B. pilosa, e milho, U decumbens e B. pilosa sem competicao, e o segundo fator dois regimes hidricos, irrigacao diaria e restricao hidrica, que correspondeu a suspensao da irrigacao desde o inicio do estagio V3 do milho ate o momento em que seus estomatos ficaram totalmente fechados. As especies B. pilosa e U decumbens agravaram em difere